Drum rocking support for carrying heavy loads



April 4, 1967 K. s. SVENDSEN 3,312,199

DRUM ROCKING SUPPORT FOR CARRYING HEAVY LOADS Filed Dec. 14, 1965 2 Sheets-Sheet 1 INVENTOR: KONRAD S. SVENDSEN AGENT p 4, 1967 K. s. SVENDSEN 3,312,199

DRUM ROCKING SUPPORT FOR CARRYING HEAVY LOADS Filed Dec. 14, 1965 2 Sheets-Sheet 2 INVENTOR:- KONRAD S. SVENDSEN BY we AGENT United States Patent Ofitice 3,312,199 Patented Apr. 4, 1967 tion of Delaware Filed Dec. 14, 1965, Ser. No. 513,803 Claims. (Cl. 122-510 The invention relates to steam boilers which are suspended from a steel structure, and is more particularly concerned with supporting, by means of rocker chairs, a portion of the boiler including the steam and water drum and the tubes connected thereto, as well as other equipment attached to the tubes such as the boiler casing.

In large modern steam generators operating at high pressures the temperature of the drum and tubes reaches a relatively high value. This results in a substantial displacement of the drum with respect to a fixed supporting structure due to thermal expansion of the drum and the tubes. Often the load carried by the drum supports exceeds one million pounds. Since the pressure at which many modern steam generators are operating approaches and sometimes rises above the critical pressure of 3206 pounds per square inch, the temperature of the steam contained in the drum and tubes may exceed 700 F. Thermal expansion of the boiler parts, therefore, may often amount to several inches.

A common method of supporting the boiler consists in suspending it from an overhead steel structure by means of drum hangers such as those disclosed in US. application Ser. No. 345,611, now Patent No. 3,263,656, filed Feb. 18, 1964, by John Kurek, I r. Because of a displacement of the drum of several inches and because of the heavy load carried by the drum hangers, such hangers must not only have a large cross sectional area, but must also be of substantial length to provide flexibility so as to prevent the resulting tensional and bending stresses from exceeding established safe limits. Thus, in large boilers generating more than one million pounds of steam per hour the overhead steel beams may be at an elevation of thirty to forty feet above the drum elevation. This requires that the boiler columns as well as the building columns roof and side Walls of the building must be extended a substantial distance above the drum elevation, which adds a considerable amount to the cost of the boiler and building structure.

While in the past drum chairs and rollers have been used in supporting relatively small boiler loads, the extremely large weight (one million pounds and more) which must be carried by the drum chairs of large modern boilers make the use of roller chairs impractical. This is so because a large number of rolls would have to be employed to support the heavy load. These rollers would require two large base plates having accurately machined rolling surfaces, one surface spaced from the other in perfect parallel relation, to insure equal distribution of the load to all rollers, lest one or the other roller would be flattened. This would defeat the purpose of the chair support and impose unpredictable stresses on the steel structure due to thermal unrelieved expansion forces.

The present invention overcomes the above problems by the use of a rocking support structure having one end thereof formed in the manner of a large diameter roller for rocking contact, and having the other end thereof organized in the manner of a fixed bearing for sliding and oscillating contact.

Furthermore, in many geographical locations boiler and building structures are exposed to horizontal shear forces caused by earthquake and Windstorm. Provisions must be made in the design of large boilers to resist these forces. When suspending a drum and boiler from drum hangers a special support must be provided to oppose the lateral forces caused by seismic and atmospheric disturbances. The present invention eliminates such special support, since the force required to overcome the frictional resistance presented by the heavily loaded rocker support disclosed herein is far in excess of the forces generally calculated as attributable to earthquake or Windstorm.

It is accordingly an important object of the invention to provide a drum support capable of carrying extremely large loads while permitting thermal expansion of the boiler and drum without undue lateral forces acting on the s eel structure.

Another object of the invention is to significantly reduce the overhead steel structure and building height when faced with the problem of supporting large boilers operating at high pressure and high temperature.

A further object of the invention is to provide a rocking drum support to carry extremely large loads wherein one end of the rocker is designed for rolling contact and the other end for sliding and oscillating contact.

A still further object of the invention is to eliminate the cost of special supports ordinarily required to oppose lateral forces caused by earthquake and Windstorm.

Other objects and advantages of the invention will become apparent from the following description of an illustrative embodiment thereof when taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a partial elevational cross section of a steam generator equipped with the herein disclosed support structure;

FIG. 2 is a plan View of the steam drum and steel structure, showing the direction in which the drum ends move due to thermal expansion;

FIG. 3 is an enlarged elevational view of the cradle and rocker support of the drum;

FIG. 4 is a plan section of the cradle and rocker when taken on line 44, of FIG. 3;

FIG. 5 is an elevational view of the cradle and rocker support of FIG. 4 when taken on line 5-5 thereof;

FIG. 6 is a side view when taken on line 6-6 of FIG.

FIGS. 7 and 8 are side views of the rocker support similar to FIG. 6, with FIG. 7 showing the rocker in the cold position and FIG. 8 in the hot position; and

FIGS. 9, 10 and 11 are side views of three other designs of the herein disclosed rocker support.

Referring now to the drawings wherein like reference characters are used throughout to designate like elements, the illustrative and preferred embodiment of the inven generator designated generally as 10 and comprising a furnace chamber 12 lined with heat absorbing tubes 14, and

including roof tubes 16 which terminate in a steam and water drum l8. This drum is supported from structural steel 20 by means of a pair of cradle and rocker supports 22, one at each end 24 of drum 18 as shown in FIG. 2. The steam generator is restrained by the surrounding steel work in such a manner that a fixed point 25 of zero horizontal expansion is established which point preferably is located approximately midway between front and rear of the boiler and at the center line 26 thereof In a top supported steam generator such as that i1- lustratively depicted in FIG. 1 a major portion of the vertical thermal expansion occurs downwardly from the center of drum 18. Thermal horizontal expansion of the tubes such as roof tubes 16 proceeds from point 25 toward drum 18, and thermal horizontal expansion of the drum proceeds from center line 26 toward each end 24 of drum 18, with the center of drum 18 slideably being anchored at 27. The resultant direction of expansion for displacement of drum ends 24 accordingly takes place along lines 3 28 and away from point 25, the point of zero expansion as indicated in FIG. 2.

Referring now to FIG. 3 the drum support comprises a cradle 30 built up of structural steel members 31 and preferably welded to drum 18. Cradle 3t includes a horizontal base plate 32 having a smooth lower surface 33. As more clearly shown in FIGS. 5 and 6, this surface is in rolling contact with the outer surface at one end of a rounded member such as a large diameter cylindrical section 34. The other end of member 34 is organized for sliding and oscillating contact by being provided with a cylindrical, concave bearing surface matching the upper contact surface of a bearing shaft 38.

As indicated in FIGS. 3 and .4, two rocker assemblies are provided for each drum cradle 30. The bearing shaft 38 of each rocker is supported by and attached to a supporting plate 40 which may be an integral part of steel structure 20.

To reduce the friction on the bearing surface 3 6 and to avoid possible seizure, in accordance with the invention, a self-lubricating bearing insert 44 is provided of the type generally known as a lubrite bearing. The use of this bearing will further reduce any lateral forces exerted on the steel structure due to thermal expansion.

FIGS. 7 and 8 show the rocker support in the cold and the hot position, respectively, with distance 46 representing the amount of displacement of each drum end due to expansion.

FIG. 9 shows a design of the herein disclosed rocking support similar to FIG. 6, but with the contact surfaces reversed. Thus, in FIG. 9 the sliding and oscillating contact surfaces is at the top end, and the rolling contact surface at the bottom end of the rocking member.

FIGS. 10 and 11 show designs similar to FIGS. 9 and 6, respectively, however, whereas in the designs illustrated in FIGS. 6 and 9 the sliding and oscillating ends of member 34 have a concave shape, those of the designs illustrated in FIGS. 10 and 11 have a convex shape.

While I have illustrated and described preferred embodiments of my invention, it is to be understood that such are merely illustrative and not restrictive and that variations and modifications may be made therein without departing from the spirit and scope of the invention. I therefore do not wish (to be limited to the precise details set forth but desire to avail myself of such changes as fall within the purview of my invention.

I claim:

1. In combination, an elongated vessel, a structure fixedly attached to said vessel and extending laterally [therefrom with respect to the longitudinal axis of said vessel, means exposing said structure and said vessel to heat causing thermal expansion forces to move said vessel in a direction which lies in the horizontal plane passing through the longitudinal axis of said vessel and is at an acute angle with respect to said longitudinal axis; a first contact surface integral with the underside of said vessel; a fixed support below said vessel and spaced therefrom, including a second contact surface facing said first contact surface; rocking means between said vessel and said fixed support for transferring the weight of said vessel onto said fixed support; one end of said rocking means having a first curvature being organized for rolling contact with one of said first and second contact surfaces; the other end of said rocking means having a second curvature being organized for sliding and oscil lating contact with the other of said first and second contact surfaces; and said second contact surface having a threedimensional support area inversely matching said second curvature.

2. The combination as defined in claim 1, wherein the other end of said rocking means is equipped with a selfl-ubrieating bearing.

3. The combination as defined in claim 1, wherein the one end of said rocking means is organized for rolling contact with said first contact surface, and the other end for sliding and oscillating contact with said second contact surface.

4. The combination as defined in claim 1, wherein said one end of said rocking means is organized for rolling contact with said second contact surface and said other end for sliding and oscillating contact with said first contact surface.

5. The combination as defined in claim 3 wherein said second contact surface comprises a convex surface and said other end of said rocking means a concave surface matching said convex surface.

6. The combination as defined in claim 3 wherein said second contact surface comprises a concave surface and said other end of said rocking means a convex surface matching said concave surface.

7. The combination as defined in claim 4, wherein said first contact surface comprises a convex surface and said other end of said rocking means a concave surface matching said convex surface.

8. The combination as defined in claim 4, wherein said first contact surface comprises a concave surface and said other end of said rocking means a convex surface matching said concave surface.

9. The combination as defined in claim 1, wherein the radius of said first curvature is a multiple of the radius of said second curvature.

10. The combination as defined in claim 9, wherein the radii of said first and of said second curvatures have a common center of rotation.

References Cited by the Examiner UNITED STATES PATENTS 59,094- 3/1938 Norway.

KENNETH W. SPRAGUE, Primary Examiner. 

1. IN COMBINATION, AN ELONGATED VESSEL, A STRUCTURE FIXEDLY ATTACHED TO SAID VESSEL AND EXTENDING LATERALLY THEREFROM WITH RESPECT TO THE LONGITUDINAL AXIS OF SAID VESSEL, MEANS EXPOSING SAID STRUCTURE AND SAID VESSEL TO HEAT CAUSING THERMAL EXPANSION FORCES TO MOVE SAID VESSEL IN A DIRECTION WHICH LIES IN THE HORIZONTAL PLANE PASSING THROUGH THE LONGITUDINAL AXIS OF SAID VESSEL AND IS AT AN ACUTE ANGLE WITH RESPECT TO SAID LONGITUDINAL AXIS; A FIRST CONTACT SURFACE INTEGRAL WITH THE UNDERSIDE OF SAID VESSEL; A FIXED SUPPORT BELOW SAID VESSEL AND SPACED THEREFROM, INCLUDING A SECOND CONTACT SURFACE FACING SAID FIRST CONTACT SURFACE; ROCKING MEANS BETWEEN SAID VESSEL AND SAID FIXED SUPPORT FOR TRANSFERRING THE WEIGHT OF SAID VESSEL ONTO SAID FIXED SUPPORT; ONE END OF SAID ROCKING MEANS HAVING A FIRST CURVATURE BEING ORGANIZED FOR ROLLING CONTACT WITH ONE OF SAID FIRST AND SECOND CONTACT SURFACES; THE OTHER END OF SAID ROCKING MEANS HAVING A SECOND CURVATURE BEING ORGANIZED FOR SLIDING AND OSCILLATING CONTACT WITH THE OTHER OF SAID FIRST AND SECOND CONTACT SURFACES; AND SAID SECOND CONTACT SURFACE HAVING A THREEDIMENSIONAL SUPPORT AREA INVERSELY MATCHING SAID SECOND CURVATURE. 